Electric clock



Dec. 5, 1933. I POOLE 1,937,529

ELECTRICv CLOCK Filed Aug. 11 1931 Patented Dec. 5, 1933 ELECTRIC CLOCK 7 Arthur F. Poole, Ithaca, N. Y.

. Application August 11, 1931-. Serial No. 556,369

5 Claims.

My invention is an electric clock and has for one of its objects the provision ofv an improved impulse mechanism for the pendulum to theend that the impulse required to keep the pendulum .5 invibration shall be uniform.

Another object of my invention is an improved contact making device including a triode and associated circuits, thereby taking advantage of the relay action of the triode to reduce the current :1 broken at the contact of the clock to a minimum.

A further object of my invention is an impulse device which will gi've'the impulse during a small arc of the pendulums swing, leaving the pendulum to swing undisturbed during the remainder iii of its'swing. While, with my' herein described impulse device, I can give the impulse at any point of the pendulums swing, I prefer to give it Just as the pendulum leaves the zero point of its swing. At thatpoint its kinetic energy is a maximum and a disturbance produces the least efict on its period; I p

A further object of my invention is the provisionof an -im'pulse device which will be simple to make and reliable in its operation. The above 47g; and other objects of my invention will be pointed out in the following specification and claims. I

i 'Referring'now to the drawing, Fig. 1 is a moreo'r-less diagrammatic view of a clock embodying my invention and Fig. 2 is a detail of the impulse roller and its mounting on the pendulum.

- In Fig. 1, 11 is the framework in which is the suspension spring 12 supporting the pendulum on which'is mounted the impulse roller 13, turning on a shaft 14 pivoted in the bridge 15 and the pendulum 10. The pendulum I0 is provided with a. bob I6 supported on a regulating" nut 17 threaded on the pendulum rod.

block l9'1'astened to the framework supports an impulse spring 18 "which is made'of a flat 4 springfs'trip and has a hump -20 therein to engage ther'oller 13. The end'28 of the spring 18 is bent at a right angle as shown to contact with'a button 22' on the end of a lever 23 pivoted at 24 in the framework. Thebutton 22 is preferably made of j 45 a metal suitable for electric contacts suchas gold or platinum and the end 21 is also provided with a tip: of similar metal to prevent oxidation. Banking screws 25 and "26 limit the motion of the lever 23 against the attraction of an electrojo" mag-net 29 on the one hand and a retractile spring 28 on the other. armature 27 is secured to the lever 23 and isfattracted by the magnet 29 when-the same is energized in a manner presently to be described.

55 Neglecting for a moment the circuit conneca tions to bring the result about, assume that when the end 21 is in contact with the button 22 the magnet 29 is de energized and when the contact between 21 and 22 is broken the magnet 291s energized. Then the pendulum swings to the left, the roller 13 encounters the hump 20 which has been held in position by the contact'of the parts 21 and 22. When the roller 13 encounters the hump 20, the impulse spring 18' is slightly lifted thus breaking contact between 21 and'22. 5 The magnet 29 is then energized and the lever 23 is drawn to the banking screw 25 against the spring 28. This leaves the spring 18 free to run down the right side of the roller 13 thus giving a push to the pendulum. When the end 21 con- 7- tacts with the button 22, the magnet 29'is at once de-energized and the retractile spring 28 lifts the lever 23 to thelevel of the screw26 carrying the spring 18 with it. The pendulum swing on to the left undisturbed, on its return to 7 the right, the roller 13 again breaks contact between 21 and 22, the magnet 29 is againmade, the lever 23 drawn against the screw 25 and the hump 20 runs down the left side of the roller l3 giving another impulse. As soon as the contact is made between 21' and 22, the magnet 29 is again tie-energized and the lever 23 returns to its normal position as shown in Fig. 1. completes. the cycle of operation. The pendulum gets an impulse at each swing for the roller 13 picks up thespring 18 at a higher level than'said roller le'avesit.

Having described the action of the magnetfi2'9, I shall now describe the circuitsneeded to bring this action about. The system consisting of the 9 0 lever 23, the retractfle spring 28, and the banking screws 25 and 26, is electrically insulated from the spring 18, which with the pendulum is grounded on the framework. Tooperate the magnet 29, I use a triode containing the usual filament 51, 95 plate 52 and grid 53. An A battery 47 heats the filament 51, a B battery 48 supplies plate current, and. a C battery 49 at certain times puts a'nega-J tive bias'on the grid. The circuit will be apparent fromthe figure, the plate 52 is connected by the 160 conductor'54 to the magnet 29, then by the wire 55 to the magnet 39 (to be described later) then by the wire 56 to the plus side of the B battery 48. The contact 21-22 controls the bias of the grid. 53 which is connected bya conductor 5'7to the. 1 05 lever 23. .The button'22 on this lever at certain times, contacts with the end 21 of the spring '18 which" is connected by the conductor with the negative pole of the C. battery 49. A grid leak 58 is connected from the grid to the filament by 11 35S i described. The wheel 30 is on a rotatable shaft 2 a conductor 59. Thebias of the grid is so chosen that when'21 and 22 are in contact the plate current is blocked, consequently at this time the magnets 29 and 39 are de-energized. When the 21 and 22, therefore any corrosion of said con-.

tacts would be undesirable. With the improved.

circuit herein shown, the grid current is on the order of ten microamperes, anamperage too small to have any deleterious elfec't onthe integrity of the contact points. Further a resistance of half a megohm may be inserted in the grid circuit without elfect on the plate current, sothe opera tionof the contacts is nctefiected by variations of resistance in the contact points. f I

There remains to-explain the operation of the magnet'39." This is to operate astep by step jumper to count the swings of the pendulum 10. To this endI have provided a ratchet wheel 36, to be driven by a pawl 31 and retained from backward rotation by a. click 32; The pawl 31 is ona lever 33 which is moved between the stops as and V 40-: motion work (notshown) serves to drive an hour 35, pivoted at 36, held to the stop 35 by a spring which is attracted'by the magnet 39 when the same is energized by plate current aspreviously 41 and has a pinion attached thereto. which drives a third wheel 42 on a shaft l3 and having a pinion 44 which drives the center wheel 45 to whichisattached the minute handio. Suitable hand at the proper ratio. Preferably the gear a ratio between the wheel 39 and the Wheel 45 is to l,'s0 that a secondhandmay be attached to the shaft 41.

WhileI have shown ajumper type of movement to. keep trackof the beats of the pendulum, evidently the currents made at each beat or" the pendulum could be used to keep an independent.

clock movement insynchronism therewith. A

'suitable independent clock movement for this f published by N. A. G. Press, Old St., London,

England. Referring to Fig. 116, page 209, the

V currents fromthe pendulumof my herein describedclock are led through the magnetfM in said figure and will thus synchronize the pendue. lum D of the slave clock with the pendulum of my clock described herein. In the description of the Shortt clock the synchronizing currents are applied each half minute, however the synchro nizer will work perfectly well if the impulses are applied at each beat of the pendulum. These impulses have .no effecton the slave pendulum until it gets slow, they then bring itinto step with the hands in spite of an occasional interruption of the synchronizing impulses, it is only necessary that during such interruption the slave pendulum does not get out of step a quarter of aperiod. When i I? the impulses are resumed the slave is soon brought roller 1-3.

up toisynchronism. Therefore the count will not be lost.

The impulse system consisting of the spring 18' and the wheel 13 should be made as light as consistent with strength. The spring 18 could be replaced by a gravity arm pivoted at 19 without departing from the spirit of my invention.

Whichwould be symmetrical with the plane of the swingofthe pendulum. In this event, the back spring 18 would be connected to the front one so both springs would be controlled by the lever 23.

i I have shown myinvention applied to a pendulum, however, it is also of use when applied to a balance wheel. In this event the impulse wheel 13 would be mounted on and rotate with the balance wheeLbeing suitably counter poised. When so used, it'will' give an impulse which is constant in amount and leaves the balance detached through alarger portion of its are thana chronometerescapement.

. pulls the lever 23 to its lower position. 1

, The impulse should be so arranged that if for any reason thecurrent is interrupted, of the contact 2l-2i2 fails to function and thelever 23,re-

mains-in its attracted position, the roller, 13 will pass underthe impulse spring 18 on therreturn of the pendulum. Tothis end the screw- 25 is so adjusted that the angleof impulse extends about i have found aseparation of a few.

45' degrees as measured from the centerof the Then, in the event of a failure of any kind, the roller will pass idly under the hump 20. It willfbe evident that the impulse givento successive swings of the pendulumissymmetrical.

That is to saythat the impulse given when, the pendulum swings to the right extends from approximately zero toa certain small angle of the pendulum swing; Thisimpulse, on the following swing of the pendulum to the left, is followedby an impulse which also starts at zero and extends to the same angle in theopposite direction. The

preceding is slightly modified by the diiference in ference is imperceptible and may be made as small I as desired by increasing thelength ofsaid spring. My herein described impulse mechanism is the electrical analogue of a chronometer escapement, the liftingof the spring 18 corresponds to the unlocking action and the subsequent fall of} the hump 20 on the circumference of the wheel-l3 to the impulse. Theunlocking is, of course, much less work than is required in a chronometer, and the impulse, being the force of a spring falling through a constant distance, is uniform. Further my device will work without ,oil on the'acting parts, due to the lightness of the acting parts themselves and the extremely small forces involved; Theabsence of oil makes for permanency of rate.

means therefor controlled by atriode. I Many changes may be made in the precise structure herein described without departing from spirit of my invention, since I claim:

1. In an electric clock the combination of a pendulum, impulse means for said pendulum adapted to contact therewith intermittently, a triode having a plate and a grid, electric circuits for said plate and grid, an electromagnet connected in the plate circuit of said triode and adapted to flexsaid impulse means and a contact device operated by said pendulum in the grid circuit'of said triode.

2. In an electric clock the combination of a pendulum, an impulse arm disposed to be engaged by said pendulum near the middle of its swing and to be detached therefrom at the end of its swing, a triode having a plate and a grid, electric circuits therefor, an electromagnet adapted to flex said arm in the plate circuit of said triode and a pendulum operated contact device in said grid circuit to open and close the same.

3. In an electric clock the combination of a pendulum, an impulse arm for said pendulum to contact therewith intermittently, a'triode having a plate and a grid, electric circuits therefor, an electromagnet in the plate circuit of said triode, an armature for said electromagnet arranged to lift said impulse arm and a pendulum operated the contact device on said armature and in said grid circuit.

4. In an electric clock the combination of a pendulum, a spring actuated impulse arm arranged to give an impulse thereto at approximately right angles to the length of said pendulum, an electromagnet, an armature therefor electrically insulated from said arm, a stop for said armature, a spring to hold said armature against said stop, a triode having a plate and a grid, an electriccircuit for said plate having said electromagnet therein and a second circuit for said grid having said arm and armature in series therein.

5. In an electric clock the combination of a pendulum, a spring actuated impulse arm arranged to give an impulse thereto at approximately right angles to the length of said pendulum, an electromagnet, an armature therefor electrically insulated from said arm, a stop for said armature, a spring to hold said armature against said stop, a triode having a plate and a grid, an electric circuit for said plate having said electromagnet therein, a second circuit for said grid having said arm and armature in series therein and a projection on said pendulum adapted to separate said arm from said armature as said pendulum passes said arm. I

ARTHUR. F. POOLE. 

